1. Field of the Invention
This invention relates to new heterocyclic compounds, their use as herbicides and to herbicidal compositions containing these new heterocyclic compounds.
2. Summary of the Invention
The present invention is directed to new heterocyclic compounds of formula I below: ##STR2## wherein X is O or NR.sup.3 in which R.sup.3 is hydrogen or alkyl; X.sup.1 is oxygen or sulfur; Y is hydrogen, halogen, cyano, alkyl, alkoxy, haloalkoxy, alkylthio or haloalkyl; Z is hydrogen, halogen, alkyl, alkoxy, haloalkoxy or haloalkyl; R.sup.1 and R.sup.2 each independently is hydrogen, alkyl, aryl or aralkyl and R is hydrogen or methyl.
Typical compounds of this invention are those of formula I above wherein Y is hydrogen, halogen of atomic number 9-35, inclusive, that is fluorine, chlorine or bromine, cyano, alkyl, alkoxy or alkylthio of 1 to 6 carbon atoms each optionally substituted by one or more halogen of atomic number 9-35, inclusive; Z is hydrogen, halogen, preferably chlorine or bromine, alkyl or alkoxy of 1-6 carbon atoms optionally substituted by halogen; R.sup.1 and R.sup.2 each independently is hydrogen, alkyl of 1 to 6 carbon atoms or aryl or aralkyl of up to 8 carbon atoms, such as phenyl, benzyl or phenethyl; and R.sup.3 is hydrogen or alkyl of 1 to 6 carbon atoms and R is hydrogen or methyl, preferably hydrogen.
Typical compounds contemplated for use within the scope of this invention include:
2-phenoxymethyl-1,3-dioxolan-4-one PA0 2-(2,4-dibromophenoxymethyl)-1,3-dioxolan-4-one PA0 2-(2-(trifluoromethyl)-4-fluorophenoxymethyl)-1,3-dioxolan-4-one PA0 2-(2,4-dimethylphenoxymethyl)-1,3-dioxolan-4-one PA0 2-(2,4-difluorophenoxymethyl)-1,3-oxathiolan-5-one PA0 2-(4-chlorophenoxymethyl)-4,4-diphenyl-1,3-oxathiolan-5-one PA0 2-(2-methoxy-4-bromophenoxymethyl)-5-methyl-1,3-dioxolan-4-one PA0 2-(2,4-di(trifluoromethyl)phenoxymethyl)-1,3-oxathiolan-5-one PA0 2-(2-(trifluoromethyl)-4-fluorophenoxymethyl)-1,3-oxathiolan-5-one PA0 2-phenoxymethyl-1,3-oxathiolan-5-one PA0 2-(2,4-dimethylphenoxymethyl)-1,3-oxathiolan-5-one PA0 2-(2-fluoro-4-methylphenoxymethyl)-1,3-dioxolan-4-one PA0 2-(4-trifluoromethoxyphenoxymethyl)-1,3-dioxolan-4-one PA0 2-(2-methoxy-4-methylophenoxymethyl)-1,3-dioxolan-4-one PA0 2-(.alpha.-methyl-phenoxymethyl)-1,3-dioxolan-4-one PA0 2-(alpha-methyl-phenoxymethyl)-1,3-oxathiolan-5-one PA0 2-(4-methylphenoxymethyl)-4-phenyl-1,3-oxathiolan-5-one PA0 2-(4-bromophenoxymethyl)-4,4-dimethyl-1,3-oxathiolan-5-one PA0 2-phenoxymethyl-1,3-oxazolidin-4-one PA0 2-(2,4-dibromophenoxymethyl)-5-methyl-1,3-oxazolidin-4-one PA0 2-(4-methylphenoxymethyl)-5-phenyl-1,3-oxazolidin-4-one PA0 2-(2-trifluoromethyl-4-fluorophenoxymethyl)-1,3-oxazolidin-4-one PA0 2-(4-methoxy-2-chlorophenoxymethyl)-1,3-oxazolidin-4-one PA0 2-(2-fluoro-4-chlorophenoxymethyl)-1,3-oxazolidin-4-one PA0 2-(2-chloro-4-bromophenoxymethyl)-3,5-dimethyl-1,3-oxazolidin-4-one PA0 2-(2,4-difluorophenoxymethyl)-1,3-thiazolidin-4-one PA0 2-(4-methyl-2-bromophenoxymethyl)-3,5-dimethyl-1,3-thiazolidin-4-one PA0 2-(2-trichloromethyl-4-chlorophenoxymethyl)-1,3-thiazolidin-4-one PA0 2-(4-ethoxy-2-chlorophenoxymethyl)-5-phenyl-1,3-thiazolidin-4-one PA0 2-(2-bromo-4-chlorophenoxymethyl)-1,3-thiazolidin-4-one PA0 2-(2-chloro-4-fluorophenoxymethyl)-1,3-thiazolidin-4-one PA0 2-(2-methyl-4-chlorophenoxymethyl)-1,3-oxazolidin-4-one PA0 2-(2-methyl-4-chlorophenoxymethyl)-3-methyl-1,3-oxazolidin-4-one PA0 2-(2-methyl-4-chlorophenoxymethyl)-3,5-dimethyl-1,3-oxazolidin-4-one PA0 2-(2-methyl-4-chlorophenoxymethyl)-5,5-dimethyl-1,3-dioxolan-4-one PA0 2-(2-methyl-4-chlorophenoxymethyl)-1,3-dioxolan-4-one
Preferred because of their herbicidal properties are those compounds of formula I wherein Y is halogen, preferably chlorine, or alkyl, preferably methyl; Z is halogen, preferably chlorine; R.sup.1 is hydrogen or alkyl, preferably methyl, R.sup.2 is hydrogen and R is hydrogen. For Example:
Expecially active are those species wherein Y and Z are halogen, preferably chlorine and R, R.sup.1 and R.sup.2 are each hydrogen. For example: 2-(2,4-dichlorophenoxymethyl)-1,3-dioxolan-4-one and 2-(2,4-dichlorophenoxymethyl)-1,3-oxathiolan-5-one.
In general the dioxolanes (X=O, X.sup.1 =O) are somewhat more active than the oxathiolanones (X=O, X.sup.1 =S), oxazolidinones (X=NR.sup.3, X.sup.1 =O) or the thiazolidinones (X=NR.sup.4, X.sup.1 =S).
It will be appreciated that when R.sup.1 .noteq. R.sup.2 that the heterocyclic compounds of the invention may exhibit geometrical isomerism. The individual isomers together with mixtures thereof are included within the scope of the invention. It will also be appreciated that certain isomers of the heterocyclic compounds of the invention have more activity than the other isomers and that it may be desirable to effect separation of the more active component.
The heterocyclic compounds of the present invention are readily prepared by synthesis methods known in the art.
The preferred method for obtaining the heterocyclic compounds of the present invention involves the condensation of a carbonyl compound with an .alpha.-hydroxy carboxylic acid or amide thereof. Thus the specific carbonyl reactant used is the appropriate substituted phenoxyacetaldehyde, such as (4-chlorophenoxy)-, (2,4-dichlorophenoxy)-, or (2-chloro-4-methylphenoxy)acetaldehyde. The .alpha.-hydroxy acid to be used includes the following: glycolic, thioglycolic, lactic, .alpha.-hydroxy-dimethylacetic or mandelic acid or an amide thereof.
Acidic catalysts are used in the condensation reaction, for example: benzene- or p-toluenesulfonic acid and activated Montmorillonite. However, I prefer to use the Lewis acid, boron trifluoride in the form of the etherate, BF.sub.3 --O(C.sub.2 H.sub.5).sub.2, which permits the condensation to be carried out successfully at ambient temperature without azeotropic removal of water. The reaction is conducted in the presence of a solvent. Suitable solvents include ethyl ether and tetrahydrofuran. Reaction products may be purified using conventional techniques. Geometric isomers are readily separated by silica chromatography.
As mentioned above the heterocyclic compounds are of interest as herbicides, preferably for pre-emergence application. The invention includes, therefore, herbicidal compositions comprising a carrier and/or a surface active agent, together with, as active ingredient, a heterocyclic compound of the invention. Likewise the invention also includes a method of combating weeds at a locus which comprises applying to the locus a heterocylic compound or composition of the invention.
The term "carrier" as used herein means a solid or fluid material, which may be inorganic or organic and of synthetic or natural origin, with which the active compound is mixed or formulated to facilitate its application to the plant, seed, soil or other object to be treated, or its storage, transport or handling.
The surface-active agent may be an emulsifying agent or a dispersing agent or a wetting agent; it may be non-ionic or ionic.
Any of the carrier materials or surface-active agents usually applied in formulating pesticides may be used in the composition of the invention, and suitable examples of these are to be found, for example, in UK patent specification No. 1,232,930.
The compositions of the invention may be formulated as wettable powders, dusts, granules, solutions, emulsifiable concentrates, emulsions, suspension concentrates or aerosols. Wettable powders are usually compounded to contain 25, 50 or 75% w of toxicant and usually contain, in addition to solid carrier, 3-10% w of a dispersing agent and, where necessary, 0-10% w of stabilizer(s) and/or other additives such as penetrants or stickers. Dusts are usually formulated as a dust concentrate having a similar composition to that of a wettable powder but without a dispersant, and are diluted in the field with further solid carrier to give a composition usually containing 1/2-10% w of toxicant. Granules are usually prepared to have a size between 10 and 100 BS mesh (1.676-0.152 mm), and may be manufactured by agglomeration or impregnation techniques. Generally, granules will contain 1/2-25% w active ingredient and 0-10% w of additives such as stabilizers, slow release modifiers and binding agents. Emulsifiable concentrates usually contain, in addition to the solvent and, when necessary, co-solvent, 10-50% w/v active ingredient, 2-20% w/v emulsifiers and 0-20% w/v of appropriate additives such as stabilizers, penetrants and corrosion inhibitors. Suspension concentrates are compounded so as to obtain a stable, non-sedimenting, flowable product and usually contain 10-75% w active ingredient, 0.5-15% w of dispersing agents, 0.1-10% w of suspending agents such as protective colloids and thixotropic agents, 0-10% w of appropriate additives such as defoamers, corrosion inhibitors, stabilizers, penetrants and stickers, and as carrier, water or an organic liquid in which the active ingredient is substantially insoluble; certain organic solids or inorganic salts may be dissolved in the carrier to assist in preventing sedimentation or as antifreeze agents for water.
Aqueous dispersions and emulsions, for example, compositions obtained by diluting a wettable powder or a concentrate according to the invention with water, also lie within the scope of the present invention. The said emulsions may be of the water-in-oil or of the oil-in-water type, and may have a thick "mayonnaise"-like consistency.
The compositions of the invention may also contain other ingredients, for example, other compounds possessing pesticidal, especially insecticidal, acaricidal, herbicidal or fungicidal properties.